My players are all new and the classic murder hobos, and they just haven´t realised it, their axctions are more of an evil party so im planing that the nex campaign will be for evil PCs. Is there any official story in 5e, preferibly for level 8th PCs?

There haven't been any official published works that assume evil characters as of yet. Arguably, you might be able to dump them into about mid-way through the Ravenloft adventure and things might work themselves out.

You could always show them some consequences for their actions and make them evil in the current one. there would still be bad guys and your story but now your players have to reconcile being wanted/hated by the cities. unable to do normal things like visit a shop without a disguise. incorporate a way for them to redeem themselves or some sort of penance. and then the next campaign just think of a story the way you did this one but just switch the roles. now your party are the ones trying to bring on some cataclysmic even and there is some party/organization devoted to stopping them. nice way to spice up both!

Thanks for you answers, Decided to them to continue with their regular campaing but now being not trusted and hated in some places, giving them a chance of redemption